1. Field of the Invention
The present invention relates to the use of an adhesive to prepare a disposable absorbent product intended for the absorption of liquids such as body liquids. The adhesive exhibits a reduced visibility through the outer sheets of the disposable absorbent product to a wearer or user, thereby improving the aesthetics of the disposable absorbent product.
2. Description of the Related Art
Disposable absorbent products currently find widespread use in many applications. For example, in the infant and child care areas, diapers and training pants have generally replaced reusable cloth absorbent articles. Other typical disposable absorbent products include feminine care products such as sanitary napkins or tampons, adult incontinence products, and health care products such as surgical drapes or wound dressings. A typical disposable absorbent product generally comprises a composite structure including a topsheet, a backsheet, and an absorbent structure between the topsheet and backsheet. These disposable absorbent products, when appropriate, usually include some type of fastening system for fitting the product onto the wearer. Adhesives, often referred to as construction adhesives, are generally used to join the different parts of the disposable absorbent product together.
For aesthetic reasons related to consumer acceptance, typical topsheet and backsheet materials are generally desired to appear opaque or white in color. One known method of achieving such opacity or whiteness of topsheet or backsheet material is to incorporate a pigment, such as titanium dioxide (TiO.sub.2), into the formulation used to prepare the topsheet or backsheet material. However, the incorporation of such pigments is generally undesirable to the manufacturer due to the additional cost incurred by the use of such pigments.
Although current disposable absorbent products have been generally accepted by the public, these products still have need of improvement in specific areas. Backsheets often used in disposable absorbent products are generally prepared from liquid-impermeable materials which function to contain liquids, such as water, urine, menses, or blood, within the absorbent core of the disposable absorbent product and to protect a wearer's outer garments from soiling. However, such impermeable backsheets are sometimes perceived by the wearer as causing the disposable absorbent product to be hot and uncomfortable. Further, the impermeability of such backsheets generally precludes the self-drying of the disposable absorbent product which would otherwise occur because of evaporation of the liquids contained therein.
Breathable nonwoven materials have therefore been developed and employed in disposable absorbent products to improve the overall performance of such disposable absorbent products. Such breathable materials are generally impermeable to liquid but are permeable to vapor. Breathable backsheets generally provide a cooler disposable absorbent product and permit some self-drying of the disposable absorbent product while it is being worn. As indicated, such breathable backsheets are intended to allow for the passage of vapor through them while retarding the passage of liquid.
An example of a breathable material useful as a backsheet in a disposable absorbent product is a breathable film comprising a polyolefin resin, such as polypropylene or polyethylene, and an inorganic filler, such as calcium carbonate. When the film is stretched during processing, the inorganic filler generally causes a network of holes to be formed in the film. Such holes are generally small enough to prevent the passage of a liquid, but are generally large enough to allow vapor to pass through the holes. Such holes have also, in certain instances, been found to provide a secondary benefit of providing a whiteness or opacity to the film material by scattering light in the same manner as solid pigment particles, thereby eliminating the need for the use of pigments in the film material.
However, when such breathable films, not including any pigments, are attached to the other components in a disposable absorbent product by the use of typical construction adhesives, a problem sometimes referred to as adhesive staining is generally encountered, wherein the applied adhesive pattern, such as lines or swirls, is visible through the breathable film. Such adhesive staining is undesirable in that it generally negatively affects the aesthetics and consumer-perceived quality of the disposable absorbent product. Although such adhesive staining might be controlled by using pigments or a higher basis weight breathable film, the use of such pigments or higher basis weight film adds additional costs to the manufacturing of the disposable absorbent product.
As such, there is a need for adhesive materials that may be used in disposable absorbent products that allow for the use of nonwoven materials, such as breathable films, that don't include pigments while not negatively affecting the aesthetics and consumer-perceived quality of the disposable absorbent product.
It is therefore an object of the present invention to provide an adhesive, which exhibits unique rheological properties, which is suitable for use in preparing a disposable absorbent product.
It is also an object of the present invention to provide a disposable absorbent product comprising a nonwoven material, such as a breathable film, which exhibits desirable aesthetic properties.
It is also an object of the present invention to use an adhesive, which exhibits unique rheological properties, to prepare a disposable absorbent product which exhibits desirable aesthetic properties.